The invention relates generally to diagnostic imaging, and more particularly, to an ablation array having independently activated ablation elements. The invention is further related to control of such an ablation array to ablate multiple ablation points simultaneously, create a linear or curvilinear ablation lesion, or ablate multiple ablation points at a given catheter position.
Heart rhythm problems or cardiac arrhythmias are a major cause of mortality and morbidity. Atrial fibrillation is one of the most common sustained cardiac arrhythmias encountered in clinical practice. Cardiac electrophysiology has evolved into a clinical tool to diagnose and treat these cardiac arrhythmias. As will be appreciated, during electrophysiological studies, multipolar catheters are positioned inside the anatomy, such as the heart, and electrical recordings are made from the different chambers of the heart. Further, catheter-based ablation therapies have been employed for the treatment of atrial fibrillation.
Conventional techniques utilize radio frequency (RF) catheter ablation for the treatment of atrial fibrillation. Currently, catheter placement within the anatomy is typically performed under fluoroscopic guidance. Intracardiac echocardiography (ICE) has also been employed during RF catheter ablation procedures. Additionally, the ablation procedure may necessitate the use of a multitude of devices, such as a catheter to form an electroanatomical map of the anatomy, such as the heart, a catheter to deliver the RF ablation, a catheter to monitor the electrical activity of the heart, and an imaging catheter. A drawback of these techniques however is that these procedures are extremely tedious requiring considerable manpower, time and expense. Further, the long procedure times associated with the currently available catheter-based ablation techniques increase the risks associated with long term exposure to ionizing radiation to the patient as well as medical personnel.
Additionally, with RF ablation, the tip of the catheter is disadvantageously required to be in direct contact with each of the regions of the anatomy to be ablated. RF energy is then used to cauterize the identified ablation sites. Further, in RF ablation techniques, the catheter is typically placed under fluoroscopic guidance. However, fluoroscopic techniques disadvantageously suffer from drawbacks, such as difficulty in visualizing soft tissues, which may result in a less precise definition of a therapy pathway. Consequently, these RF ablation techniques typically result in greater collateral damage to tissue surrounding the ablation sites. In addition, RF ablation is associated with stenosis of the pulmonary vein.
Moreover, a pre-case computed tomography (CT) and/or magnetic resonance imaging (MRI) as well as electroanatomical (EA) mapping systems may be employed to acquire static, anatomical information that may be used to guide the ablation procedure. However, these systems disadvantageously provide only static images and are inherently unfavorable for imaging dynamic structures such as the heart.
Another issue frustrating intravenous and intra-arterial ablation is the non-integration between ultrasonic imaging arrays and ablation arrays, each of which are positioned in a body via separate catheters. As described above, this typically results in multiple catheters being disposed in a patient for a single interventional procedure. This is particularly prevalent in ICE. Specifically, it is not uncommon for some ICE procedures to utilize three to four catheters inside the heart chambers in the course of the procedures. Adding to the multiplicity of catheters is that catheters used to deliver RF ablation energy are separate from the catheter used to visualize the ablation catheters and target anatomy. This poses two general drawbacks. First, by separating the imaging and ablation catheters, the physician must use a 2D imaging device to guide an independent catheter being manipulated in three dimensions. Understandably, this can be difficult and time-consuming. Second, conventional ablation techniques utilize RF ablation catheters, which, as described above, require the physician to physically contact each desired ablation point. As a typical ICE procedure will include 100-200 ablation points, the ablation process can become quite tedious and lengthy. In addition to ICE, the same or similar drawbacks are also experienced in transesophageal echocardiography (TEE), laparoscopy, arthroscopy, and other procedures characterized by a disintegration of imaging and ablation devices.
Additionally, conventional ablation devices are characterized by an array of globally controlled ablation elements. That is, all of the ablation elements of the ablation array are activated/deactivated as a group. This results in an ablation beam defined by a high amplitude main lobe and a series of generally off-centered, low amplitude secondary lobes. As a result of this conventional construction and use, only a single ablation point can be ablated at a time. Since most ablation procedures involve approximately 100-200 ablation points, one-at-time ablation can be quite time consuming and tedious.
There is therefore a need for an integrated imaging and ablation catheter that provides intracorporeal imaging and that also allows for the ablation, assessment, and reablation, if necessary, without ablation point contact. It would also be desirable to have an ablation device capable of ablating multiple ablation points simultaneously.